Computer methods, apparatus and articles of manufacture therefor, are disclosed for text-characterization using a finite state transducer that along each path accepts on a first side an n-gram of text-characterization (e.g., a language or a topic) and outputs on a second side a sequence of symbols identifying one or more text-characterizations from a set of text-characterizations. The finite state transducer is applied to input data. For each n-gram accepted by the finite state transducer, a frequency counter associated with the n-gram of the one or more text-characterizations in the set of text-characterizations is incremented. The input data is classified as one or more text-characterizations from the set of text-characterizations using the frequency counters associated therewith.